Children are fascinated by shiny, glitter-like materials. For example, the multi-directional reflection of light from glitter-like materials captivates children's attention and stimulates their sense of sight. Therefore, when children use writing instruments capable of making written markings containing glitter-like materials, their attention span and creativity are increased. Consequently, it is highly desirable to provide such writing instruments. Capillary-action markers capable of making written markings containing glitter-like materials are particularly desirable as such writing instruments are capable of making relatively larger written markings, and therefore provide a relatively greater glitter effect.
Writing instruments capable of making written markings containing glitter-like materials are known. For example, valve-action markers capable of making written markings containing glitter-like materials have been developed. Typically, such valve-action markers utilize a spring-loaded nib, which opens a valve to an ink reservoir when depressed (e.g., against a writing surface), thereby allowing the ink to flow from the ink reservoir to the nib. The valve-action markers require more parts than conventional capillary-action markers, and consequently their manufacture is more complicated and costly.
Additionally, valve-action markers are problematic in that the glitter-like materials tend to settle to the bottom of the ink reservoir when the valve-action markers are not in use. Therefore, the user typically has to violently shake the marker prior to using same in order to effect distribution of the glitter-like materials throughout the ink composition and ensure that the ink composition delivered to the marker nib contains sufficient amounts of glitter-like material to produce the desired visual effect. Additionally, the user typically has no means to verify that the glitter-like material has been adequately distributed throughout the ink composition because the marker barrel is opaque. The user must also subsequently depress the nib against a writing surface to open the valve to the ink reservoir and allow delivery of the ink composition to the nib. These shaking and depressing actions may not be intuitive to children.
U.S. Pat. No. 6,120,590 to Miyamoto discloses a ball point pen containing a water-based, thixotropic gel ink having metallic lustrous color. Such thixotropic gel inks, however, are too viscous to be successfully adapted for use in many writing instruments, including capillary-action markers.
Conventional capillary-action markers contain an ink reservoir and a nib in fluid communication therewith. Such markers typically include an ink composition having a low viscosity because the adhesive forces (between the ink composition and the channel walls of the reservoir and/or nib) must exceed the cohesive forces of the ink composition to permit movement of the composition by capillary action. Incorporating glitter-like materials (e.g., aluminum flakes) into the low viscosity ink compositions of capillary-action markers is difficult because such glitter-like materials tend to settle out of the ink compositions. Even when the glitter-like materials are adequately suspended in the ink compositions, the marker's reservoir fibers typically undesirably filter the glitter-like materials and become clogged over time. Accordingly, over time, the marker is rendered incapable of making written markings containing glitter-like materials.
U.S. Pat. No. 6,561,713 discloses an exemplary capillary-action marker capable of making markings containing glitter-like materials. The '713 patent, however, only teaches and suggests aqueous or water-based inks containing metallic pigment particles having a particle size between 1 micron and 12 microns because “if the particle size of the aluminum pigments is too large, greater than 12 microns, they will not flow through the pathways of the filler and the nib.” See '713 patent at column 3, lines 44-46. Consequently, the glitter effect provided by markings made with such markers is small, owing to the small size of the pigment particles. Furthermore, the '713 patent explicitly teaches against including dyes as colorants (i.e., rather than pigments) in such metallic ink compositions.